The Wide-Field Imager (WFI) is the outcome of a joint project between the European Southern Observatory (ESO), the Max-Planck-Institut für Astronomie in Heidelberg (Germany) and the Osservatorio Astronomico di Capodimonte near Naples (Italy). It was installed at the 2.2 m MPG/ESO telescope in 1998 December. A mosaic of eight CCDs provides a large field of 34×33 arcmin which allows us to obtain detailed views of extended celestial objects down to very faint magnitudes. WFI is the first of a new generation of survey facilities at ESO and will be replaced by OmegaCAM on the 2.6 m VLT Survey Telescope (VST) at Paranal in the near future.